The present application is directed to a biological treatment system and an assembly for supporting biomass derived from bacteria present in or seeded into the sludge or wastewater for treating the sludge or wastewater. More particularly, the present application is directed to an assembly of generally structural corrugated sheets and generally non-structural intermediate members mounted between pairs of the corrugated sheets wherein the corrugated sheets, when bonded together, provide structural support for the assembly. The assembly typically includes multiple corrugated sheets with an intermediate member preferably sandwiched between each of the corrugated sheets of the assembly.
Treating sludge and wastewater by passing the sludge and wastewater through media having a relatively large surface area with a biomass growing thereon to remove ammonia nitrogen (NH3—N) or other such contaminants from and to reduce the biochemical oxygen demand (BOD) of the sludge and wastewater is known. For example, U.S. Pat. No. 4,599,174 ('174 patent), which is incorporated herein by reference in its entirety, discloses a fixed-film biological distribution system wherein contaminated waste is biologically digested by microorganisms retained on corrugated packings or media. The media are typically constructed of structural sheets with bacteria growing thereon, such as is disclosed in the '174 patent, or a non-structural textile material that is mounted to a heavy and relatively expensive stainless steel support structure for immersion in the sludge and wastewater. The sludge and wastewater is exposed to the bacteria growing on the surfaces of the media, which biologically treats the sludge and wastewater, either aerobically, anoxically or anaerobically, depending upon the type of well-known bacteria used in the system.
The non-structural fabric or textile material usually includes multiple loops to increase the surface area for bacteria growth and is typically more efficient in supporting the biomass for treating the sludge and wastewater when compared to the structural sheet material. However, the non-structural fabric or textile material is typically mounted to a relatively high-cost and heavy stainless steel mounting structure. In contrast, the structural sheet material is less efficient in treating the sludge and wastewater than the non-structural fabric or textile material but is comparatively light and less expensive than the stainless steel support structure. In addition, the stainless steel support structure provides little or no surface area for growth of the treatment bacteria. One non-limiting example of a suitable fabric or textile sheet having multiple loops is disclosed in U.S. Pat. No. 5,771,716, the disclosure of which is hereby incorporated by reference.
It would be desirable to construct a sludge and wastewater treatment medium having both the advantages of the structural sheet material and the non-structural fabric or textile material in an individual assembly. Specifically, it would be desirable to construct a sludge and wastewater treatment medium having a relatively low cost, a lightweight and having a high relatively efficiency in treating the sludge and wastewater. The present invention generally provides these advantages.